1. Technical Field
The present invention relates to hearing evaluation and hearing aid fitting. More particularly, the present invention relates to virtual electroacoustic audiometry for unaided, simulated aided, and aided hearing evaluation.
2. Description of the Prior Art
The human auditory system processes sounds from a complex three-dimensional space via the external, middle, and inner ear, as well as via the complex neural pathways that lead to the auditory cortex within the brain. A measurable hearing loss, due to various conductive, sensorineural, or central auditory disorders, affects a significant percentage of the human population, particularly elderly persons. Rehabilitation via hearing aids remains the only viable option for those types of hearing impairments that cannot otherwise be medically treated or surgically alleviated.
Advances in hearing aids and fitting technologies are continuously being made. Today's ear-level hearing aids, i.e. in-the-ear (ITE), behind-the-ear (BTE), in-the-canal (ITC), and completely-in-the-canal (CIC) types, are more cosmetically appealing due to improvements in electronic and mechanical miniaturization. More significant, however, is the increasing availability of advanced hearing aid signal processing schemes, such as adaptive filtering and multi-band dynamic compression.
As manufacturers are continuously developing new hearing aids with unique signal processing schemes, a hearing aid dispensing professional is faced with the increasingly difficult task of prescribing and selecting a hearing aid for a hearing-impaired individual from the available selection. A cursory look at available hearing aid processing schemes reveals an impressive array of categories, sub-categories, and associated acronyms that are baffling to most hearing aid dispensing professionals (see Mueller, H. G., A Practical Guide To Today's Bonanza of Underused High-Tech Hearing Products, The Hearing Journal, vol. 46, no. 3, pp. 13-27, 1993).
Today, optimal fitting of prescription hearing aids remains an elusive goal in auditory rehabilitation. The fundamental problem is that there are numerous electrical, acoustic, physical, and other parameters that affect hearing aid performance. These parameters include signal processing schemes, electronic circuit adjustments, size of hearing aid, insertion depth, venting size, patient controls, and life-style related factors that must be considered when prescribing and fitting a hearing aid. These hearing aid parameters are not only complex and highly interrelated, but also vary according to the unique interaction of the hearing device with the hearing-impaired individual.
Generally, the in situ performance characteristics of a hearing aid cannot be predicted with today's conventional fitting instrumentation and methods. Dissatisfaction among hearing aid user's, partially due to poor hearing aid prescription fitting, is manifested by a high return rates, often exceeding 20% according to industry reports.